The present invention relates to a gripping means and more particularly, to a gripping means of an injection machine, which provides a sufficient force to securely grip the molds when injecting material into the molds.
Conventionally, the injection molding machine comprises two molds between which the molding material is injected to form a product having a configuration in accordance with the inner shape of the two molds. The two molds are respectively disposed to a movable plate and a fixed base, the mold disposed to the movable plate is moved toward the other mold disposed to the fixed base by a long stroke cylinder, a gripping means mechanically connected to the movable plate is then actuated to provide a force to move the mold disposed to the movable plate to contact the mold disposed to the fixed base in order to securely engage the two molds together when injecting molding material into a space enclosed by the two molds. The molding material is injected into the molds by a high pressure injecting means and therefore a very large force exerts against the respective inner surface of the two molds and has a tendency to push the two molds apart. In this situation, the two molds could be slightly separated from each other and the gripping means could be damaged and furthermore, the product formed between the two molds looses a pre-determined configuration thereof because some material is formed between a slit defined between the two molds.. In order to improve the drawback, the gripping means must equipped with a cylinder with larger diameter so as to provide a sufficient force to resist against the outward force of the molds by the action of injecting material into the molds, however, there are at least four rods extending through the movable plate such that the movable plate can move along the four rods, therefore, the space between the four rods restricts the using of the cylinder with larger diameter and thus a sufficient force to maintain a secure engagement of the two molds is difficult to be achieved. Preferably, the force ratio received between the cylinder outputs and the molds is larger than 2 which ensures a secure engagement between the two molds and the conventional gripping means mentioned above usually achieves the standard only by increasing the size of the injection molding machine which incurs a high cost.
The present invention intends to provide a gripping means of an injection molding machine and which provides a sufficient force to secure the two molds together and therefore mitigates and/or obviates the above-mentioned problems.